Okay, sorry about all my fish topics, but now I need some more help. My fantail goldfish just died and I'm not sure why. I'm worried that it may have been a parasite or disease which may have contaminated my tank. He was the only fish in the tank.

Okay, so I bought him 2 weeks ago from wal-mart. He was kept in a bowl until yesterday. He was having issues when he was in the bowl. He was only using one of his gills and seemed to stay at the surface. So I got worried and put him in my tank yesterday hoping it would give him more oxygen (even though it hadn't been cycled yet) and make him better. He started to get better, using his gill more and more as time passed. First he stayed on the bottom of the tank, then explored. After about the third hour of him being in the tank, he stayed on the bottom, with the gravel. Today, I noticed he was barely moving around again, this time at the bottom and would just let himself bump into the gravel. the left side of my tank has a lot of current because of the filter and whenever he went over there (obviously) he struggled. Well, about 15 minutes ago, I saw him over swimming in that area and then just float up to the top and I came over. He wasn't moving any of his fins, but his gills and mouth were going really fast. After a couple minutes, he got pulled down to where the filter tubes pulls in the water and his body kinda wrapped around it, not moving.

I took him out and he was dead. I now notice little red areas on his body. One underneath his eye and two on the side of his body on the other side. After thinking about it a bit, I realized he wasn't eating (he'd go up to the top when the food was there, but wasn't interested) last night or this morning. And I haven't seem him.. go to the bathroom.. since he's been in the tank.

Help!

Okay, so is there anything I need to do to make the tank water safe for other fish/fish types or should I just change and clean the whole tank?

Another question: I've been told goldfish can survive in 2.5 gallons of water and thrive as long as the tank is clean and water quality is good. So how can they not survive in a 10 gallon and need to be in a 20-30 gallon? I have a 10 and want some fish, but I'm thinking goldfish aren't the answer for me.

The general rule is 1 goldfish per 10 gallons, minimum. :)

That was the only goldfish in the tank. Only fish in the tank period.

there are lots of reasons why the fish died (many of which i've already mentioned in your other fish threads). did you employ a heater? a thermometer? fish that hang around at the bottom could be due to being cold.

how big was your goldfish?

I tend to massacre fish....so I can't really help much. Like shatzy said, there could be a number of reasons why the fish died (damn things are so difficult to care for...too many variables).

I suppose shock could have killed it, though, if it had been recently transferred, or if you didn't wait a day between filling the tank with new water and putting him in (I remember reading something about waiting at least 24 hours).